Device for securing bits of bone together

Abstract

Device for securing bits of bone together, particularly small-sized bits of bone, for example bits of metatarsal head, in the form of a spindle comprising an elongate shank ( 1 ) followed, after a breakable region ( 2 ), by a fixator element ( 3 ) extending frustoconically to reduce in diameter in the direction of the anterior end ( 4 ), with a screw thread the pitch of which decreases progressively from the anterior end and of which the crests of the thread lie inside a coaxial geometric cylinder (D), the anterior end forming a self-drilling end.

1 . Device for securing bits of bone together, including small-sized bits of bone, comprising: 
 a spindle having an longitudinal axis and comprising    an elongate shank ( 1 ) with a weakened region ( 2 ) the weakened region configured to allow the elongate shank to be broken,    a fixator element ( 3 ) following the weakened region, the fixator element having a frustonconical surface extending frustoconically so that the fixator element reduces in diameter in a direction of a free anterior end ( 4 ) of the fixator element, and,    a screw thread on the frustoconical surface,    the screw thread having    a pitch decreasing progressively from said anterior end and,    bottoms formed by said frustoconical surface,    crests which lie inside a geometric cylinder (D) coaxial with the axis of the spindle,    the screw thread covering an entire length of the fixator element from said anterior end to a posterior end,    said anterior end ( 4 ) being beveled and forming a drilling end, so as to allow said anterior end to be screwed into the bits of bone.    
     
     
         2 . Device according to  claim 1 , wherein, 
 the weakened region is in the form of a groove ( 2 ) of roughly triangular cross section ( 4 ) with a point defining an acutely angled groove bottom,    which groove facilitates breakage, by angular tilting, of the fixator element with respect to the shank, while at the same time being able to withstand stresses generated as the fixator element is driven into the bits of bone.    
     
     
         3 . Device according to  claim 1 , wherein sections of the threads are roughly triangular with one face inclined toward a front of the fixator element and one face roughly perpendicular to the axis of the spindle toward a rear of the fixator element ( 3 ).  
     
     
         4 . Device according to  claim 1 , wherein, 
 the device is one of a set of devices comprising a number of like devices,    dimensions of the fixator element ( 3 ) of each of the like devices varying as to at least one of length, screw thread crest diameter, cone angle, and pitch.    
     
     
         5 . Device according to  claim 4 , wherein, 
 the like devices in the set have different lengths of fixator element ( 3 ), and    a diameter of a geometric cylinder in which the crests of the thread lie remains constant.    
     
     
         6 . Device according to  claim 2 , wherein sections of the threads are roughly triangular with one face inclined toward a front of the fixator element and one face roughly perpendicular to the axis of the spindle toward a rear of the fixator element ( 3 ).